Everyone should listen to Kofi Annan's claims that the massacre in Houla is a "tipping point" in the crisis in Syria, a United Nations human rights spokesman said today.
Robert Colville, spokesman for the human rights commissioner, said the UN's initial investigations had shown the killing of 108 people in Houla, 49 of whom were children, was likely the work of people linked to the regime.
Yesterday Britain announced the expulsion of the Syrian charge d'affaires and two other diplomats in coordinated global action aimed at condemning last week's events in Houla, which is in the Homs province of Syria.
Kofi Annan, a former UN Secretary General, who has been working to broker a resolution to the long-running clashes in Syria, warned yesterday the massacre could be a tipping point.
And speaking to the Radio 4 Today programme, Mr Colville said: "In Syria it's been not such a major threat (as that seen in Libya before the international intervention) but it's been a horror story really for 14 months now, with many thousands of people killed, and torture, and really horrendous stuff going on.
"You need concrete action. I think Kofi Annan's efforts are essential. You have to try and he has been very frank about how difficult it is.
"His work yesterday was important and I think his statement that it is a tipping point is something everyone should listen too."
Mr Colville said he believed it would be possible to track down the perpetrators of the massacre, highlighting the cases in Latin America relating to crimes which took place 20 or 30 years ago.
He said: "I hesitate to name individuals but we have recommended, the High Commission of Human Rights has recommended repeatedly, the case of Syria be referred to the International Criminal Court (ICC), which is the court competent to judge really serious crimes, such as what happened last week, crime against humanity.
Pressed on what action could be taken, Mr Colville added: "The Security Council on Sunday did issue an extremely strong condemnation which is something they were not doing only a few months ago.
"But in terms of concrete actions like referral to the ICC, that has not yet happened.
"In these situations, you get a lot of politics as well, state politics, we come at it from a legal point of view, from a human rights law point of view, and to us it is fairly clear what needs to happen.
"But at a political level other things come into play unfortunately."
Mr Colville said the Security Council's responsibility to protect was a fairly recent concept and one which is not universally accepted.
He said: "It was invoked in the case of Libya, and I think the jury is still out as to how successful the transformation was in Libya, but at least a large scale massacre was averted and it seems one was on the cards - I think that is why states did react there, because the threat against an entire city was overt and could not be ignored."